i am posting two links,
First is of Human Rights Commission of Pakistan,
Second is of Punjab Prisons Pakistan
Unfortunately an overall statistics can only be traced back to 2014, while Punjab prisons has an updated database. other key stat's and prison conditions such as:
Blasphemy
Burning s
Corporal punishment
Death penalty
Domestic violence
Killings
Prisons
Sectarianism & sectarian violence
Suicide
can be found on HRCP website.
http://hrcp-web.org/hrcpweb/campaigns/
http://www.prisons.punjab.gov.pk/prisoners-statistics
hope this helps.